The present invention relates generally to apparatus for coupling spacecraft, and more particularly to a spacecraft berthing mechanism having a construction that minimizes the overall radial projection of the berthing mechanism from an associated spacecraft hull.
Various types of apparatus have been proposed for accomplishing a temporary or permanent mechanical connection between two spacecraft so that different operations may be performed. Such operations include the passage of crew members between the spacecraft for crew-tended operations and logistical support and the passage of modules containing expendable supplies and equipment needed for space-borne experiments and manufacturing processes. The operations may also include the assembly and structural expansion of spacecraft and the on-orbit repair and maintenance of spacecraft.
An example of a docking apparatus is disclosed in commonly assigned U.S. Pat. No. 4,903,919 issued to Caldwell C. Johnson and Maxime A. Faget on Feb. 27, 1990 and entitled "Apparatus and Method for Docking Spacecraft". The aforementioned docking apparatus is particularly useful for coupling an Industrial Space Facility (ISF) spacecraft module (designed by Space Industries, Inc. of League City, Tex., the assignee of the present invention) to the Space Transportation System (also referred to as the Space Shuttle Orbiter and developed in the United States by the National Aeronautics and Space Administration (NASA)). The ISF spacecraft module is described in more detail in commonly assigned U.S. Pat. No. 4,728,061, issued to Caldwell C. Johnson et al. on Mar. 1, 1988, entitled "Spacecraft Operable In Two Alternative Flight Modes", and in commonly assigned U.S. Pat. No. 4,834,325 issued to Maxime Faget et al on May 30, 1989 entitled "Modular Spacecraft System". The module is generally cylindrical in shape, with a plurality of the modules being capable of being joined together in a side-by-side relationship. The individual spacecraft modules may be carried into orbit by the NASA Space Shuttle and joined together to form an orbiting laboratory in which research and development may be carried out.
The ISF docking apparatus described in U.S. Pat. No. 4,903,919 is preferably mounted to the NASA Space Shuttle and includes a berthing mechanism attached to one end thereof. A complementary berthing mechanism is permanently attached to the ISF spacecraft module so that when the two berthing mechanisms are brought together, a pressure-tight joint is formed therebetween.
An example of a berthing mechanism that may be used in connection with the ISF docking apparatus is disclosed in more detail in commonly assigned U.S. Pat. No. 5,040,749, issued to Caldwell C Johnson on Aug. 20, 1991 and entitled "Spacecraft Berthing Mechanism With Discrete Impact Attenuation Means". Such a berthing mechanism may also be employed for coupling individual ISF spacecraft modules together. Generally, the berthing mechanism comprises a cylindrical peripheral flange that defines a passage-way and that is adapted for attachment to a port or other aperture of a spacecraft. The flange includes a forward interface surface and a rearward rim for attaching the flange to the port. Alignment rails are selectively positioned about the outer edge of the flange in order to provide guidance during coupling of two berthing mechanisms.
When a berthing mechanism is mounted to the port of a spacecraft, it typically protrudes radially outward from the spacecraft pressure hull. If the spacecraft is to be transported into orbit in the payload bay of another spacecraft, e.g., the NASA Space Shuttle, this protrusion may significantly affect the maximum allowable size the spacecraft pressure hull may have while still being capable of fitting within the payload bay. The degree to which the berthing mechanism affects the size of the spacecraft pressure hull largely depends on the size of the corresponding hatchway.
Presently, NASA is contemplating a uniform hatch size for the modules of the NASA Space Station. NASA has decided that the hatches for the NASA Space Station modules should be large enough to allow passage of a standard double rack. A standard double rack is approximately 36.times.41.5.times.80 inches. The space module hatches would therefore need to be relatively large in size to allow safe passage of a double rack.
In order to provide uniformity within the spacecraft industry, it is desirable that the hatches for the ISF space modules also be large enough to allow passage of a double rack. A berthing mechanism of conventional geometry, however, that is sized to allow access of a double rack, would be relatively large and, therefore, would have a significant effect on the allowable size of the ISF spacecraft module to which it is attached.